Your Wife is entitled to work the second she has officially entered the UK, like Mupsuit says.
Your Wife is lucky if your friend can offer her job [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]
All the Employer needs to do is have a copy of the revelant pages in her passport (Name and details page and Visa stamp page at the very least if i remeber correctly) most want proof of address and bank details as well (from my experience with my Wifes Job). The tax office have information on their website and im sure your friend can contact his friendly tax office for more information if needed.
My Wife was lucky in the fact that the majority of people were working with her both managment and fellow workers were Visa holders of one sort or another so no one needed to look up the details.
